Single sideband generator



May 2, 1m

J. GUTTMAN ETAL SINGLE SIDEBAND GENERATOR I Filed March 25, 1964 8Sheets-Sheet l '2 MODULA 7E0 RF our F To TRANSMITTER GENERA TOR :3 15 vsm/r/ms/z "-72 R F COUNTER L GENERA r02 14 cAue Ai'a/e a j 00 0N5 MCktmemva 5002a ONE. N am: MEGA era: a, Y5 TA! 1;

mfmcvae gowns/2 0 Elf/V 050, A70? our r0 com/m2 OVEN 0N5 MmAn ru CON m0;BUFF R 007 POM/2 warm/12 v01 74015 51mm v :74 655 ,efaam 702 V INVENTORSJULIUS GUTTMAN KIRK FOURCHER JONAS M. SHAPIRO Wzn m ATTORNEY w W67 J.GUTTMAN ETAL 3,317,840

SINGLE SIDEBAND GENERATOR Filed March 25, 1964 8 Sheets-Sheet 2 May 2,J. GUTTMAN ETAL SINGLE SIDEBAND GENERATOR Filed March 25, 1964 8Sheets-5heet 6 QTTQRNEY y 2, 1967 J. GUTTMAN ETAL 3,317,840

SINGLE SIDEBAND GENERATOR Filed March 25, 1964 8 Sheets-Sheet 7 C6261.

TH/Ql) UPPER SIDEBA N0 ATTORNEY M y W67 J. GUTTMAN E-TAL SINGLE SIDEBANDGENERATOR 8 Sheets-Sheet. 8

Filed March 25, 1964 INVENTORS JULIUS GUTTMAN KIRK FOURCHER JONAS M.SHAPIRO ATTORNEY United States Patent Office 3,317,349 Patented May 2,1967 3,317,840 SINGLE SlDEiiAND GENERATOR Julius Guttman, White Plains,N.Y., and Kirk Fourcher, Ridgefield, and Jonas M. Shapiro, Stamford,Conn., assignors to Manson Laboratories Inc., Wilton, Conn., acorporation of (Ionnecticut Filed Mar. 25, 1964, Ser. No. 354,526 17Claims. (Cl. 325-13 7) The present invention relates to a singlesideband generator. More particularly, the present invention relates toa radio transmitter circuit arrangement for transmitting a singlesideband signal.

An object of the present invention is to provide a new and improvedsingle sideband generator.

In accordance with the present invention, a single sideband generatingcircuit arrangement comprises a radio frequency generator having aplurality of inputs and an output for producing sideband signals and formodulating audio modulations on a radio frequency carrier. An audiofrequency generator having an input and an output connected to an inputof the radio frequency generator produces audio modulating signals froman upper sideband input and a lower sideband input. Upper sidebandinputs and lower sideband inputs are supplied to the input of the audiofrequency generator. A synthesizer having an output connected to aninput of the radio frequency generator supplies stable frequencies tothe radio frequency generator. A counter having an input connected tothe output of the radio frequency generator and another input indicatesfrequencies of signals produced by the single sideband generatingcircuit arrangement. A calibrator having an input connected to an inputof the radio frequency generator and to the other input of the countersupplies a reference frequency standard signal for the radio frequencygenerator and for the counter. An output connected to the output of theradio frequency generator derives the modulated radio frequency signalsfrom the radio frequency generator.

In accordance with the present invention, an audio frequency generatorfor producing audio modulating signals comprises an upper sideband audiounit having an input and an output utilizing an upper sideband input forproducing at its output an upper sideband audio modulating signal. Theupper sideband audio unit comprises a filter connected to the input ofthe upper sideband audio unit for passing frequencies below a firstpredetermined level and for passing frequencies above a secondpredetermined level, an amplifier, and a coupling which couples thefilter to the output of the upper sideband audio unit through theamplifier. An upper sideband input is supplied to the input of the uppersideband audio unit. A lower sideband audio unit having an input and anoutput utilizes a lower sideband input for producing at its output alower sideband audio modulating signal. The lower sideband audio unitcomprises a filter connected to the input of the lower sideband audiounit for passing frequencies below a first predetermined level and forpassing frequencies above a second predetermined level, an amplifier,and a coupling which couples the filter to the output of the lowersideband audio unit through the amplifier. A lower sideband input issupplied to the input of the lower sideband audio unit. A frequencyshift keying unit having inputs and an output utilizes a frequency shiftkeying input signal for producing at its output a frequency shiftedsignal in which a mark is represented by a signal having a firstfrequency and a space is represented by a signal having a secondfrequency different from the first frequency. The frequency shift keyingunit comprises an oscillator connected to an input of the frequencyshift keying unit and having outputs for producing mark and spacesignals, a gate connected to inputs of the frequency shift keying unitand to the outputs of the oscillator for gating the outputs of theoscillator, a phase shifter connected between another input of thefrequency shift keying unit and the gate for phase inverting thefrequency shift keying input signal and for controlling the gatetherewith, and a coupling which couples the gate to the input of each ofthe upper and lower sideband audio units through the output of thefrequency shift keying unit. A frequency shift keying input signal issupplied to the inputs of the frequency shift keying unit. A continuouswave unit having inputs and an output utilizes a continuous wave D.C.input signal for producing at its output a continuous wave signal. Thecontinuous wave unit comprises an oscillator connected to an input ofthe continuous wave unit and having an output and being energized by thecontinuous wave D.C. input signal for producing a tone signal ofpredetermined frequency, a gate connected to the inputs of thecontinuous wave unit and to the output of the oscillator for gating theoutput of the oscillator, a filter, and a coupling which couples thegate to the output of the continuous wave unit through the filter. Acontinuous wave D.C. input signal is supplied to the inputs of thecontinuous wave unit.

In accordance with the present invention, a radio frequency generatorfor producing sideband signals and modulating audio modulations on aradio frequency carrier comprises a frequency doubler having an inputand a pair of outputs for doubling a frequency supplied to it. A onemegacycle per second reference frequency standard signal is supplied tothe input of the frequency doubler to produce a 2 megacycles per secondoutput signal at the output of the frequency doubler. An upper sidebandbalanced modulator has a pair of inputs and an output. A lower sidebandbalanced modulator has a pair of inputs and an output. An output of thefrequency doubler is coupled to an input of the upper sideband balancedmodulator and supplies the 2 megacycles per second output of thefrequency doubler to the upper sideband balanced modulator. An uppersideband audio modulation is supplied to the other input of the uppersideband balanced modulator to produce at the output of the uppersideband balanced modulator a modulated double sideband 2 megacycles persecond radio frequency carrier with the carrier partially suppressed.The other output of the frequency doubler is coupled to an input of thelower sideband balanced modulator for supplying the 2 megacycles persecond output of the frequency doubler to the lower sideband balancedmodulator. A lower sideband audio modulation is supplied to the otherinput of the lower sideband balanced modulator to produce at the outputof the lower sideband balanced modulator a modulated double sideband 2megacycles per second radio frequency carrier with the carrier partiallysuppressed. An upper sideband crystal filter eliminates frequenciesbelow 2 megacycles per second. A lower sideband crystal filtereliminates frequencies above 2 megacycles per second. A sidebandcombiner having a pair of inputs and an output isolates the upper andlower sideband crystal filters from each other and mixes the upper andlower sideband signals to produce a 2 megacycles per second doubleindependentsideband suppressed-carrier signal at its output. The outputof the upper sideband balanced modulator is connected to an input of thesideband combiner through the upper sideband crystal filter. The outputof the lower sideband balanced modulator is connected to the other inputof the sideband combiner through the lower sideband crystal filter. Aradio frequency amplifier having an input connected to the output of thesideband combiner, another input and a pair of outputs amplifies thesignal at the output of the sideband combiner. A relay is connected tothe other output of the frequency doubler. A gate coupled between therelay and the other input of the radio frequency amplifier reinserts thecarrier suppressed by each of the upper sideband balanced modulator andthe lower sideband balanced modulator in the radio frequency carrier. Amixer has an input connected to an output of the radio frequencyamplifier, another input and an output. A frequency tripler having aninput and an output triples a frequency supplied to it. The onemegacycle per second reference frequency standard signal is supplied tothe input of the frequency tripler to produce a 3 megacycles per secondsignal at its output. A frequency divider having an input connected tothe output of the frequency tripler and an output divides the outputsignal of the frequency tripler in half to a 1500 kilocycles per secondsignal. The output of the frequency divider is coupled to the otherinput of the mixer to produce a double independent sideband signalmodulated on a 500 kilocycles per second carrier at the output of themixer. A low-pass filter eliminates frequencies above 500 kilocycles persecond. A bandswitch having a plurality of bandswitch contacts and aswitch arm connected at one end to an output contact is adapted toselectively contact at its other end one of the plurality of bandswitchcontacts. The output of the mixer is coupled to selected contacts of thebandswitch contacts of the bandswitch through the low-pass filter tosupply a 500 kilocycles per second double independent sideband signal tothe last-mentioned selected contacts of the bandswitch contacts. Theother output of the radio frequency amplifier is coupled to selectedother contacts of the bandswitch contacts of the bandswitch to supply a2 megacycles per Second double independent sideband signal to thelast-mentioned selected other contacts of the bandswitch contacts. Aradio frequency mixer has an input connected to the output contact ofthe bandswitch, another input and an output. Variable frequencyoscillator stable frequencies are supplied to the other input of theradio frequency mixer to produce a difference frequency output signal atthe output of the radio frequency mixer. An output coupled to the outputof the radio frequency mixer derives selected sideband signals and audiomodulated radio frequency carriers from the radio frequency generator.

In order that the present invention may be readily carried into effect,it will now be described with reference to the accompanying drawings,wherein:

FIG. 1 is a schematic block diagram of an embodiment of the singlesideband generating circuit arrangement of the present invention;

FIGS. 20 and 2b are a schematic block diagram of an embodiment of aradio frequency generating circuit arrangement of the single sidebandgenerating circuit arrangement of FIG. 1;

FIGS. 3a, 3b, 3c and 3d are a schematic block diagram of an embodimentof an audio frequency generating cir-' cuit arrangement of the singlesideband generator of FIG. 1;

FIG. 4- is a schematic block diagram of an embodiment of a simplifiedsynthesizer circuit arrangement of the single sideband generatingcircuit arrangement of FIG. 1; and

FIG. 5 is a schematic block diagram of an embodiment of a calibrator orreference standard of the single sideband generating circuit arrangementof FIG. 1.

In the figures, the same components are indicated by the same referencenumerals. V

The single sideband generator of the present invention is extremelystable and versatile and utilizes the filter method of single sidebandgeneration. The single sideband generator comprises an RF generator orconverter 11, and AF generator or modulator 12, a synthesizer 13, acalibrator or reference standard 14 and a fre quency counter 15.

The AF generating circuit arrangement or modulator 12 supplies an audiosignal and modulations from direct 100 milli-watts peak effective power.

and remote upper and lower sideband levels to the RF generating circuitarrangement or converter 11. The synthesizer circuit arrangement 13supplies stable frequencies to the RF generator 11. The counter 15indicates the frequencies produced by the single sideband generatingcircuit arrangement. The calibrator or reference standard 14 suppliesthe reference standard for the counter 15 and supplies the referencestandard for the fixed frequency generators in the RF generator orconverter. The calibrator or reference standard 14 may also supply thereference standard for the synthesizer 13, if desired. The outputs ofthe modulator or AF generator 12, the synthesizer13 and the calibratoror reference standard 14 are thus connected to the inputs of theconverter 11, the output of the converter 11 is connected to the inputof the counter 15, and the output of the calibrator is connected to theinput of the counter. The output sidebands are derived from the outputof the converter 11.

The converter or RF generator 11 utilizes the filter method of sidebandgeneration. The single sideband crystal filters operate at 2 megacyclesper second. The RF generator comprises all the mixers and sidebandgenerators of the system. The normal IF frequency is 2 megacycles or1.750 megacycles per second with separate modulators and filters foreither sideband over the frequency range 300 to 6000 cycles from thecarrier. A side step mixer is used to provide a 500 kilocycle per secondsignal for the 2 to 8 megacycles per second band. The 500 kilocycles persecond IF frequency is selected because the lower IF must be used toprevent spurious outputs for the 2 to 8 megacycles per second RF range.This is produced by beating the 2 megacycles sidebands against a 1500kilocycles per second signal derived from the master source of thecalibrator 14; the 2 megacycles per second IF being used in the 8 to 32megacycle RF range. A low-pass filter in the output of the 500 kilocycleunit insures that all spurious products outside of the IF are down db.The carrier insertion is handled at 2 megacycles per second and offers avariable zero to 40 db range with an infinity position capable ofgreater than 60 db carrier rejection.

In the converter 11, two separate 6 kilocycles per second audio channelsare placed as upper and lower sidebands about a suppressed carrier inthe frequency range of 2 to 32 megacycles per second with an outputpower of V The converter or RF generator 11 comprises a mixer stage, twointermediate amplifier stages and an output stage. A balanced mixer andseven synchronously-tuned circuits provide a minimum of 70 db rejectionto image and variable frequency oscillator frequencies. Adequate bandoverlap is provided and the frequency bands are chosen so that thesynthesizer may be made to read the carrier frequency directly withoutmodification to the digital frequency readout.

The modulator or audio frequency generator 12 comprises two audioamplifiers, a teletype FSK or frequency shift key frequency shiftadapter, a continuous wave unit and a break-in unit. There are two audioamplifiers, each being used for only one sideband, so that any type ofinput maybe handled in one channel while another type of input may behandled in the other channel. This also permits one input to be switchedto two outputs, thereby permitting double side-band production. Inputprovisions are incorporated in the modulator 12 for continuous wave,multiplex continuous wave and frequency shift key or FSK signals. Themodulator or AF generator 12 also includes input provisions for a localmicrophone and a remote control box. The power supply provides theoperating voltages for the AF and RF generators.

The frequency synthesizer 13 functions on the indirect method ofsynthesis utilizing double superheterodyne circuitry to discipline threefree-running variable frequency oscillators, each phase locked to a onemegacycle frequency standard. The synthesizer 13 is continuously tunableover the frequency range of 2 to 34 megacycles, with each frequencyhaving a stability of one part in per day. A single highly stablereference standard comprising a crystal controlled oscillator is used todiscipline the synthesizer so that each of the output frequencies has astability equal to that of the reference frequency. The pulling range ofthe one rnegacycle oscillator is sufficient to permit continuouscoverage between the normal synthesizer intervals. The true carrieroutput frequency is read directly on the counter without the need forany mixers.

The counter 15 provides a direct visual readout of the RF generator 11output frequencies in the range of 2 to 34 megacycles per second. Nomixers or adders are utilized so that the readout is direct and is thetrue operating frequency of the single sideband generator. An accuracyof one count would produce with a one second count period a readoutaccuracy of one cycle at any RF frequency. The reference for the counter15 is the calibrator 14.

The modulator or AF generator 12 may comprise the modulation arangementof FIGS. 3a, 3b, 3c and 3d. The AF generator 12 includes the inputswitching to select the mode of eXciter operation and amplifies themodulating signal to be fed to the RF generator or converter 11. The APgenerator provides its own supply voltage and the supply voltages forthe RF or single sideband generator. The converter, RF generator orsingle sideband generator 11 provides low level modulation of an RFcarrier and filters the carrier to provide sideband operation. The basicRF carrier is povided by the synthesizer 13 which provides continuouslytunable frequencies from 2 to 34 megacycles per second at a stability ofone part in 10 per day. The RF output of the single sideband generator11, which is a signal within the frequency band of 1.75 to 32 megacyclesper second, is fed to the RF amplifier sections of an externaltransmitter, not shown in the figures. The output frequencies of the RFgenerator 11 are also fed to the counter 15 which then directlyindicates the actual carrier frequency of the exciter or RF generator.

The audio frequency generator 12 provides full input switching for theexciter or RF generator 11. The modes of operation available are localmicrophone or handset, remote, with or without automatic gain control,and direct lines, continuous wave keying and frequency shift keying.Each sideband may be independently operated in the same or differentmodes, since each has its own function switch. Only the upper sidebandcircuit is discussed hereinafter, since both the upper and lowersideband circuits are identical.

A first upper sideband function switch 21, a second upper sidebandfunction switch 22, a third upper sideband function switch 23, a fourthupper sideband function switch 24 and a fifth upper sideband functionswitch 25 each have eight switch positions 1, 2, 3, 4, 5, 6, 7 and 8. Afirst lower sideband function switch 26, a second lower sidebandfunction switch 27, a third lower sideband function switch 28, a fourthlower sideband function switch 29 and a fifth lower sideband functionswitch 31 each have eight switch positions 1, 2, 3, 4, 5, 6, 7 and 8.

In each of the function switches 21, 22, 23, 24, 25, 26, 27, 28, 29 and31 the number 1 position is OFF, the number 2 position is Test, thenumber 3 position is Continuous Wave, the number 4 position is LocalMicrophone, the number 5 position is Remote Line, the number 6 positionis Remote Line Automatic Gain Control, the number 7 position is DirectLine and the number 8 position is Frequency Shift Keying.

With the function switches in the number 4 or Local Microphone position,a dynamic microphone 32 or handset is connected to the proper inputjack. The voice input is fed through the first upper sideband functionswitch 21 and the upper sideband audio section comprising a low- 6 passfilter 33, a high-pass filter 34 and four audio amplifier stages 35, 36,37 and 38. The low-pass filter 33 has an 8 kilocycle cutoff and thehigh-pass filter 34 passes only frequencies above 200 cycles per second.The effective input frequency range to the audio amplifier 35, 36, 37and 38 is 300 to 6000 cycles per second.

Part of the output of the final audio stage 38 is fed back through anautomatic gain control amplifier 39 and the second upper sidebandfunction switch 22 to all the audio stages 35, 36, 37 and 38 as anautomatic gain control voltage. The major part of the output of thefinal audio stage 38 is fed through two emitter followers 41 and 42. Theemitter follower 52 supplies the audio signal as the upper sidebandmodulation to the RF generator or converter 11 through the third uppersideband function switch 23 and the output terminal 43.

The emitter follower 41 feeds the audio signal through armature 44d andcontact 45g of relay &4, the relay being in energized condition, andswitch arm 46 and contact 46a of a switch 46, to headphones 47 formonitoring. The relay 44- is energized when a talk switch 48 of themicrophone 32 or a handset 49 is closed, or may be continuouslyenergized with a transmit-standby switch 51 in its closed or transmitposition. When the relay 44 is energized, it applies B plus voltage ofplus and plus 200 volts to the RF generator from a source 52 and asource 53 via the armature 442 and the contact 451' and output terminal54 and via the armature 44 and the contact 45k and output terminal 55.When the relay 44 is energized, it energizes the transmit lamp 56 whenit closes the annature 44] to the contact 45k. The energized relay 44changes the upper sideband/lower sideband input of the headphones 47from the audio output 57 and 58 of the receiver to the audio output ofthe RF generator via armatures 44b and 44d and energizes an external T/Rindicator to indicate the transmit condition via the armature 44c andthe contact 45a.

It is thus seen that the local handset switches 48 and 51 control the T/R or transmit-receive relay 44. The output of the microphone 32 is fedto the input of the upper and lower sideband audio amplifier sectionsand the amplifier automatic gain control is energized when the functionswitches are in their number 4 position. The output of the audioamplifier is fed to the converter or RF generator 11 and the audio levelmay be read on an audio level meter 61, when the function switches arein their number 4 position. When the function switches are in theirnumber 4 position, sidetone is fed into the handset 49 and when thepress-to-talk switch 48 is released, the receiver audio is connected tothe headphones 47. The switches 48 and 51 enable either sidetone to bemonitored on the handset earphone or a headphone.

With the function switches in the number 4 or Local Microphone position,the voice input is also fed through the first lower sideband functionswitch 26 and the lower sideband audio section comprising a low-passfilter 62, a high-pass filter 63 and four audio amplifier stages 64, 65,66 and 67. The low-pass filter 62 has an 8 kilocycle cutoff and thehigh-pass filter 63 passes only frequencies above 200 cycles per second.The effective input frequency range to the audio amplifiers 64, 65, 66and 67 is 300 to 6000 cycles per second.

Part of the output of the final audio stage 67 is fed back through anautomatic gain control amplifier 68 and the second lower sidebandfunction switch 27 to all the audio stages 64, 65', 66 and 67 as anautomatic gain control voltage. The major part of the output of thefinal audio stage 67 is fed through two emitter followers 69 and 71. Theemitter follower 69 supplies the audio signal as the lower sidebandmodulation to the RF generator or converter 11 through the third lowersideband function switch 23 and the output terminal 72.

The emitter follower 71 feeds the audio signal through armature 44b andcontact 450 of the relay 44, the relay being in energized condition, andswitch arm 46 and con- Line position,

tact 46b of the switch 46, to the headphones 47 for monitoring.

With the function switches in the number 7 or Direct Line position, theupper sideband input is fed directly to the RF generator 11 from theinput terminal 73 via the third uper sideband function switch 23 and theoutput terminal 43. The upper side band input is also fed through thefirst upper sideband function switch 21 to the upper sideband audiosection, so that the direct line signal may be monitored in theheadphones 47. Information may thus be fed directly to the RF generator11 without any intermediate amplification or processing in the audiosection. This permits the very lowest intermodulation in the system. Theaudio sideband amplifier is utilized only to provide a sidetone signalon the local handset 49. The single sideband generator may be energizedmanually or remotely.

With the function switches in the number 7 or Direct Line position, thelower sideband input is fed directly to the RF generator 11 from theinput terminal 74 via the third lower sideband function switch 28 andthe output terminal 72. The lower sideband input is also fed through thefirst lower sideband function switch 26 to the lower sideband audiosection, so that the direct line signal may be monitored in theheadphones 47.

With the function switches in the number 6 or Remote Line Automatic GainControl position, the upper sideband input is fed from the inputterminal 75 to the upper sideband audio section via the first uppersideband function switch 21 in the same manner as the audio input whenthe function switches are in the number 4 position, except that therelay 44 is energized only by the standby-transmit switch 51 or a remotestandby-transmit switch. The sideband amplifier automatic gain controlis energized.

With the function switches in the number a or Remote Line Automatic GainControl position, the lower sideband input is fed from the inputterminal 76 to the lower sideband audio section via the first lowersideband function switch 26.

With the function switches in the number or Remote the same operationensues as when the function switches are in the number 6 position,except that no automatic gain control is fed back to the audio amplifierstages. A balanced phantom or unbalanced line may be :fed to the remoteinputs 75 and 76. The sideband or audio amplifier without automatic gaincontrol amplifies this signal and feeds it to the converter 11 and theaudio level meter '61. The single sideband generator may 'be turned onmanually or remotely. Sidetone may be monitored by a remote handset.

With the function switches in the number 8 or Frequency Shift Keying orFSK position, the FSK input is fed from the input terminal 77 to an FSKsection which functions as an FSK converter. The FSK section isenergized by the fourth upper side-band function switch 24 which appliesplus 28 volts DC. to oscillator and gate stages of the FSK section. Theoscillator stage comprises a 2425 cycles per second oscillator 78 and a1575 cycles per second oscillator 79 and the gate stage comprises a gate81 connected to the output of the oscillator 78 and a gate 82 connectedto the output of the oscillator 79.

The oscillator 78 provides a 2425 cycles per second Mark signal which isfed to the mark gate 81 as the controlled input. The oscillator 79provides a 1575 cycles per second Space signal which is fed to the spacegate 82 as the controlled input. The switching input to each of thegates 81 and 82 is the FSK input from the input terminal 77, which issupplied directly to the space gate 82. The FSK input is inverted by aphase inverter 83 for proper phase'relationship before it is applied tothe mark gate 81.

The FSK input may be a zero milliamp Space/ 60 milliamp Mark, minus 30milliamp Space/plus 3O milliamp Mark, or a zero milliamp Space/ milliampMark signal,

any one of which will operate the gates 81 and 82. The output of thegates 81 and 82 is a frequency-shifted signal in which a Mark isrepresented by 2425 cycles per second and a Space is represented by 1575cycles per second. The FSK signal is thus inverted in the lower sidebandand normal in the upper sideband. The upper sideband is fed through thefirst upper sideband function switch 21 in the same manner as the audioinput in the number 4 position, except that the relay 44 is energizedonly by the standby-transmit switch 51 or a remote standby-transmitswitch. The upper sideband is thus fed through the first upper sidebandfunction switch 21 to the RF generator 11 through the output terminal43. The sideband amplifiers are used only for sidetone monitoring. Thesingle sideband generator may be energized manually or remotely. Any ofthe three common Teletype signals may be utilized.

With the function switches in the number 8 of FSK position, the FSKsection is energized by the fourth lower sideband function switch 29which applies the plus 28 volts DC. to the oscillator and gate stages ofthe FSK section. The lower sideband is fed through the first lowersideband function switch 26 in the same manner as the audio input in thenumber 4 position and the lower sideband is fed through the first lowersideband function switch to the RF generator 11 through the outputterminal 72.

With the function switches in the number 3 or Continuous Wave position,the plus 28 volt D.C. energizing voltage is applied from the inputterminal 84 to a continuous wave section via the fourth upper sidebandfunction switch 24 and the fourth lower sideband function switch 29. Thecontinuous wave section comprises a one kilocycle per second oscillator85, a gate 86 connected to the output of the oscillator 85, and alow-pass filter 87 connected to the output of the gate 86.

The plus 28 volts DC. is applied to the oscillator which provides theaudio frequency input to the gate 86. The gate 85 is switched on and offby the keying input from the input terminal 88. The output of the gate86 is fed through the low-pass filter 87, with a cutoff of 4 kilocyclesto eliminate switching transients, to the third upper and lower sidebandfunction switches 23 and 28, respectively, whence it is fed to the RFgenerator 11 via the output terminals 43 and 72, respectively. The keyedone kilocycle frequency is also fed through the first upper and lowersideband function switches 21 and 26, respectively, to the audioamplifiers of the upper and lower sideband audio sections, so that itmay be monitored on the headphones 47.

The keying input from the input terminal 88 is fed through a break-indelay to energize the relay 44. The break-in delay arrangement comprisesa phase inverter 89, a driver amplifier 91 connected to the output ofthe phase inverter 89, and a relay 92 connected to the output of thedriver amplifier 91. The output of the relay 92 energizes the relay 44.The break-in delay arrangement becomes immediately activated, but has arelatively long delay time, of approximately 0.1 second, so that therelay 92 remains energized when the keying is repeated at a relativelyrapid rate.

The number 3 position thus permits the sending of continuous wave with aregular telegraph key; the fast makeshow break relay 92 being utilizedto permit the appropriate break-in action with an accompanying receiver.The one kilocycle tone is gated on and off when the key is activated.The sideband amplifier is utilized only as a sidetone monitor in thenumber 3 position. When the key is released, the receiver output may beheard in the headphones 47.

With the function switches in the number 2 or Test position, the onekilocycle oscillator 85 provides a constant tone which is fed to thesingle sideband generator and may also be monitored in the headphones 47if the standbytransmit switch 51 is in the transmit position. The onekilocycle tone is fed to the single sideband generator or RF generator11 through the upper and lower sideband audio sections and is used foralignment and testing purposes. The audio sideband amplifier automaticgain control is operative. The level of the upper and lower sidebandmodulations fed to the RF generator 11 may be read on the meter 61 whenthe meter is switched to the proper sideband via switch arm 93 andcontact 93a or contact 93b. The local handset 49 may monitor the outputof the sideband amplifier. 7

With the function switches in the number 1 or OFF position, the input tothe filters and audio amplifiers is grounded by the first upper andlower sideband function switches 21 and 26, respectively, and the outputto the RF generator 11 is grounded by the third upper and lower sidebandfunction switches 23 and 28, respectively. No sidetone may be heard. Thechannel is thus completely deactivated.

The meter 61 may be switched so that the switch arm 93 contacts thecontact 93a to read the upper sideband audio voltage level to the RFgenerator. The switch arm 93 may be switched to contact the contact 93bto read the lower sideband audio voltage level to the RF generator. Themeter 61 may be switched OFF so that it has no input when the switch arm93 is moved to contact the contact 930.

The converter, single sideband generator or RF generator 11 of FIG. 1may comprise the converter of FIGS. 2a and 2b. The converter or RFsingle sideband generator of FIGS. 2a and 2b produces the sidebandsignals, impresses or modulates the modulation output of the AFgenerator or modulator 12 on the RF carrier, and amplifies the resultantmodulated RF signal to the proper level for transmitter operation. TheRF generator also provides for the reinsertion of the suppressedcarrier.

A modulated intermediate frequency is generated prior to the generationof the actual RF output in order to maintain the sideband producingfilters at a practical quantity. A one megacycle per second referencesignal from a reference source such as, for example, an internal onemegacycle crystal-controlled oscillator, or from the calibrator 14, issupplied to the RF generator of FIGS. 2a and 211 via an input terminal101. The one megacycle reference or calibration signal is doubled infrequency in a frequency doubler 102. The 2 megacycle output of thedoubler 102 is fed through an RF amplifier 103 to an upper sidebandbalanced modulator 104 and through an RF amplifier 105 to a lowersideband balanced modulator 106. The upper sideband modulation from themodulator or AF generator 12 is fed to the balanced modulator 104through an input terminal 107 and the lower sideband modulation fromsaid modulator or AF generator is fed to the balanced modulator 106through an input terminal 108.

The output of each balanced modulator 104 and 106 is a modulated doublesideband 2 megacycle RF carrier with the carrier partially suppressed.The modulated double sideband 2 megacycle RF carrier produced by thebalanced modulator 104 is fed to a buffer amplifier 109 which drives acrystal filter 111. The upper sideband crystal filter 111 eliminates allfrequencies below 2 megacycles per second. The modulated double sideband2 megacycle RF carrier produced by the balanced modulator 106 is fed toa buffer amplifier 112 which drives a crystal filter 113. The lowersideband crystal filter 113 eliminates frequencies above 2 megacyclesper second. Both filters 111 and 113 greatly attenuate the carrierfrequency as well.

The outputs of the filters 111 and 113 are fed to a sideband combiner114 which functions to isolate the filters 111 and 113 from each otherand to mix the upper sideband and lower sideband signals. The output ofthe sideband combiner 114, which is the sum of the two sideband inputs,is a double independent-sideband suppressedcarrier signal. The doubleindependent-sideband suppressed-carrier signal produced by the sidebandcombiner 114 is fed to an RF amplifier 115. The 2 megacycle output ofthe doubler 102 is also fed to a-relay 116 as a carrier control. The 2megacycle output signal of the doubler 102 energizes the relay 116 andoperates a carrier reinsert gate 117 which is connected to the RFamplifier and which permits the carrier to be reinserted, up to fulllevel, in said RF carrier.

One output of the RF amplifier 115 is fed through a second RF amplifier118 to the upper two ranges, represented by contacts 119s and 119d, of abandswitch 119. The other output of the RF amplifier 115 is fed to amixer 121. The one megacycle reference or calibration signal supplied tothe input terminal 101 is fed to a frequency tripler 122 which triplesit and produces a 3 megacycles per second output signal. The 3 megacyclesignal produced by the frequency tripler 122 is supplied to adivide-by-two divider 123 which halves it and produces a 1500 kilocyclesper second output signal. The 1500 kilocycle output signal of thedivider 123 is supplied to the mixer 121 via a buffer amplifier 124.

The mixer 121 mixes the 2 megacycle double independent-sidebandsuppressed-carrier signal from the RF amplifier 115 with the 1500kilocycle signal from the buffer amplifier 124 and produces a differenceoutput which is a double independent-sideband signal about a 500kilocycle carrier. The carrier may be completely or partiallysuppressed. The double inclependent-sideband signal modulated on a 500kilocycle carrier produced by the mixer 121 is fed through an RFamplifier 125 and a low-pass filter 126 to the lower two ranges,represented by contacts 119a and 115%, of the bandswitch 119. Thelow-pass filter 126 functions to eliminate frequencies above 500kilocycles per second.

Variable frequency oscillator frequencies from the synthesizer 13 aresupplied to an input terminal 127 of the converter arrangement of FIGS.2a and 2b. The synthesizer frequencies supplied to the input terminal127 are fed to an RF mixer 128 and the bandswitch 119 output, comprisingthe generated intermediate frequency which contains the desiredintelligence on each sideband, is also fed to the RF mixer 128. Thebandswitch 119 feeds 1.75 to 3.75 megacycles per second to the RF mixer128 when the switch arm 119 contacts the bandswitch contact 11%. Thebandswitch 119 feeds 3.5 to 7.5 megacycles per second to the RF mixer128 when the switch arm 119 contacts the bandswitch contact 1191). Thebandswitch 119 feeds 7 to 15 megacycles per second to the RF mixer 128when the switch arm 119 contacts the bandswitch contact 1190. Thebandswitch 119 feeds 15 to 32 megacycles per second to the RF mixer 128when the switch arm 119 contacts the bandswitch contact 119d- The bandsof frequencies from the synthesizer are 2.25 to 4.25 megacycles persecond, 4 to 8 megacycles per second, 9 to 17 megacycles per second, and17 to 34 megacycles per second. The modulated RF frequencies, 500kilocycles in the lower two bands and 2 megacycles in the upper twobands, are selected for optimum freedom from spurious harmonics, thelowest variable frequency oscillator frequency being five times theintermediate RF, 'and for best sideband separation, the sidebands beingseparated by 2 megacycles in the high frequencles.

The difference output of the RF mixer 128 is fed through three tuned RFamplifier stages 129, 131 and 132, respectively, to a relay 133. Therelay 133 insures radio silence while the single sideband generator istuned. In the tune condition, the relay 133 switches the output of thesingle sideband generator to the counter 15 via the output terminal 134,so that the single sideband generator may be accurately tuned to thedesired frequency. In the operate condition, the sideband signalsproduced by the single sideband generator are switched to thetransmitter, not shown in the figures, via the output terminal 135.

A meter switch 136 enables a meter 137 to monitor the levels of the onemegacycle reference signal, the synthesizer signals, the RF output andthe upper sideband and lower sideband modulation inputs. All thesections of the meter switch 136 are grounded in the OFF position.

FIG. 4 is a schematic block diagram of an embodiment of a simplifiedsynthesizer circuit arrangement of the single sideband generatingcircuit arrangement of the present invention. The synthesizer 13supplies stable frequencies to the radio frequency mixer 128 of the RFgenerator 11 and may comprise any suitable known synthesizer circuitarrangement. A preferred embodiment of synthesizer 13, however, is thatdisclosed in copending patent application Ser. No. 844,982, filed Oct.7, 1959, entitled 2 to 34 Megacycle Synthesizer Circuit Arrangement andnow abandoned. The synthesizer circuit arrangementof FIG. 4 is asimplified version of the synthesizer circuit arrangement of saidcopending application; it being understood that the preferred embodimentof the synthesizer circuit arrangement is that disclosed in saidcopending patent application. The stable frequencies produced by thesynthesizer circuit arrangement 13 are supplied to the radio frequencymixer 128 to produce a difference frequency output signal at the outputof said mixer.

The synthesizer utilizes an indirect method of producing the outputfrequencies, each of which is electronically phase locked throughdiscriminators to a stable one megacycle per second internal or externalstandard frequency. A double superheterodyne type of circuit is usedwith one free-running variable frequency oscillator being disciplined bymeans of two other variable frequency oscillators, and all threeoscillators under the control of the one megacycle standard. Thevariable frequency oscillator has pull-in and hold-in characteristicswhich are instantaneous and equal over the entire band, with continuousfrequency error correction less than five degrees of one cycle ascompared to the standard reference.

The tuning controls provide straight line tuning in which any frequencychange across'the entire band is directly proportional to rotation ofthe controls, as described in said copending application. Thesynthesizer provides over 64,000 highly stabilized output signals in therange of 2 to 34 megacycles per second. In addition, the referencefrequency source of the synthesizer has an internal crystal oscillatorwhich operates at one megacycle per second and is utilized to disciplineall output frequencies. A temperature controlled oven maintains thecrystal at its optimum operating temperature.

If higher stability than that provided by the internal crystal isdesired, any suitable reference standard of superior stability whoseoutput is one megacycle or 100 kilocycles at one volt may be utilized todiscipline the output frequencies. The one megacycle calibrator orreference standard 14, for example, may be SO utilized. The referencestandard 14 may also be utilized to monitor the frequency of theinternal crystal.

The stable output frequencies are provided by three free-runningvariable frequency oscillators in a double superheterodyne type ofcircuit with each of the oscillators disciplined, through phase detectorfed reactors, by the one megacycle standard frequency. The threefreerunning variable frequency oscillators are the main variablefrequency oscillator, the kilocycle variable frequency oscillator andthe one kilocycle variable frequency oscillator. The desired frequencyis selected by operation of a bandswitch, as described in said copendingapplication, to one of the four bands and by rotation of the two manualtuning controls until the frequency appears on a digital readoutcounter, as described in said copending application.

The synthesizer of FIG. 4 comprises a reference frequency source, a mainloop which develops the output frequency, and two incremental loopswhich control the output of the main loop in 10 kilocycle and onekilocycle steps. The different circuits and loops are all disciplined bythe reference frequency signal so that all the available outputfrequencies have the same stability as the reference frequency.

The main loop comprises a reactance-controlled, variable frequencyoscillator whose output frequency is controlled by the D.C. voltage ofthe phase detector within the loop. The main loop includes two mixerstages and two IF or intermediate frequency stages. This resembles adouble superheterodyne circuit whose output, instead of a conventionalaudio signal, is a D.C. voltage with an amplitude that is determined bythe phase coincidence between the second IF signal and the output of theone kilocycle loop.

The one megacycle reference frequency is fed to the spectrum generatorcircuit which produces kilocycle pulses and a pulse-modulated 100kilocycle sine wave having a repetition 'rate of 20.4 to 38.4 megacyclesper second. The sine wave is fed to the main loop and the 100 kilocyclepulses are simultaneously fed to the 10 kilocycle and one kilocycleloops.

The outputs of the spectrum generator and the main loop variablefrequency oscillator are mixed in the first mixer stage to produce adifference that is the first intermediate frequency. The output of the10 kilocycle incremental frequency loop is mixed with the first IFsignal in the second mixer to produce a difference that is the secondIF. The second IF is compared in the main loop phas detector to theoutput of the one kilocycle loop for phase coincidence. The output ofthe phase detector disciplines the variable frequency oscillator of themain loop, locking it to the selected frequency.

The variable frequency oscillators of the incremental frequency loopsare each disciplined through phase detector stages by the 100 kilocycleoutput pulses of the spectrum generator. The three reference inputs tothe main loop, which are the 20.4 to 38.4 megacycle sine wave, the 10kilocycle loop output and the one kilocycle loop output and which areall derived from the same reference frequency signal, serve todiscipline the variable frequency oscillator in the main loop.

As a consequence of the three loops, the output frequencies of thevariable frequency oscillator in the main loop are disciplined at threepoints by signals which are derived from the single reference frequencysignal. The stability of the output frequencies is therefore the same asthe stability of the one megacycle reference signal. The outputnof themain loop is fed to a divider circuit which passes it through unchanged,divide by one, or divides it by 2, 4 or 8 depending upon the desiredoutput frequency, to provide the four output bands of synthesizerfrequencies.

FIG. 5 is a schematic block diagram of an embodiment of a calibrator orreference standard of the single sideband generating circuitarrangement. Any suitable reference standard may be utilized as thereference standard 14. Thus, for example, a controlled crystal frequencysource of the type of FIG. 5 may be utilized. This, in effect may besimilar to the reference source of the synthesizer circuit arrangement13.

In the circuit arrangement of FIG. 5, a crystal controlled oscillatorproduces a reference standard one megacycle output to the RF generator11 and a one megacycle output to the counter 15. The crystal whichcontrols the oscillator is controlled in an oven to provide the optimumstability conditions.

The counter 15 may comprise any suitable frequency counter arrangementknown. The function of the counter 15 is to indicate the frequenciesproduced 'by the single sideband generating circuit of the presentinvention.

While the invention has been described by means of specific examples andin specific embodiments, we do not wish to be limited thereto, forobvious modifications will occur to those skilled in the art withoutdeparting from the spirit and scope of the invention.

What we claim is:

13 1. Single sideband generating circuit arrangement comprising, incombination,

radio frequency generating means having a plurality of inputs and anoutput for producing sideband signals and for modulating audiomodulations on a radio frequency carrier;

audio frequency generating means having an input and an output connectedto an input of said radio frequency generating means for producing audiomodulating signals from an upper sideband input and a lower sidebandinput;

means for supplying upper sideband inputs and lower sideband inputs tothe input of said audio frequency generating means;

synthesizer means having an output connected to an input of said radiofrequency generating means for supplying stable frequencies to saidradio frequency generating means;

counter means having an input connected to the output of said radiofrequency generating means and another input for indicating thefrequencies of signals produced by said single sideband generatingcircuit arrangement;

calibrator means having an output connected to an input of said radiofrequency generating means and to the other input of said counter meansfor supplying a reference frequency standard signal for said radiofrequency generating means and for said counter means; and

output means connected to the output of said radio frequency generatingmeans for deriving the modulated radio frequency signals from said radiofrequency generating means.

2. Single sideband generating circuit arrangement comprising, incombination,

radio frequency generating means having a plurality of inputs and anoutput for producing sideband signals and for modulating audiomodulations on a radio frequency carrier;

audio frequency generating means having an input and an output connectedto an input of said radio frequency generating means for producing audiomodulating signals from an upper sideband input and a lower sidebandinput, said audio frequency generating means comprising,

upper sideband audio unit means having an input and an output utilizingan upper sideband input for producing at its output an upper sidebandaudio modulating signal, means for supplying an upper sideband input tothe input of said upper sideband audio unit means, lower sideband audiounit means having an input and an output utilizing a lower sidebandinput for producing at its output a lower sideband audio modulatingsignal, means for supplying a lower sideband input to the input of saidlower sideband audio unit means, frequency shift keying unit meanshaving inputs and an output utilizing a frequency shift keying inputsignal for producing at its output a frequency shifted signal in which amark is represented by a signal having a first frequency and a space isrepresented by a signal having a second frequency different from saidfirst frequency, means for supplying a frequency shift keying inputsignal to the inputs of said frequency shift keying unit means, continuous wave unit means having inputs and an output utilizing a continuouswave input signal for producing at its output a continuous wave signal,and means for supplying a continuous wave input signal to the inputs ofsaid continuous wave unit means;

synthesizer means having an output connected to an input of said radiofrequency generating means for supplying stable frequencies to saidradio frequency generating means;

counter means having an input connected to the output of said radiofrequency generating means and another input for indicating thefrequencies of signals produced by said single sideband generatingcircuit arrangement;

calibrator means having an output connected to an input of said radiofrequency generating means and to the other input of said counter meansfor supplying a reference frequency standard signal for said radiofrequency generating means and for said counter means; and

output means connected to the output of said radio frequency generatingmeans for deriving the modulated radio frequency signals from said radiofrequency generating means.

3. Single sideband generating circuit arrangement comprising, incombination,

radio frequency generating means having a plurality of inputs and anoutput for producing sideband signals and for modulating audiomodulations on a radio frequency carrier;

audio frequency generating means having an input and an output connectedto an input of said radio frequency generating means for producing audiomodulating signals from an upper sideband input and a lower sidebandinput, said audio frequency generating means comprising,

upper sideband audio unit means having an input and an output utilizingan upper sideband input for producing at its output an upper sidebandaudio modulating signal, said upper sideband audio unit means comprisingfilter means connected to the input of said upper sideband audio unitmeans for passing frequencies below a first predetermined level and forpassing frequencies above a second predetermined level, amplifier means,and means coupling said filter means to the output of said uppersideband audio unit means through said amplifier means, means forsupplying an upper sideband input to the input of said upper sidebandaudio unit means, lower sideband audio unit means having an input and anoutput utilizing a lower sideband input for producing at its output alower sideband audio modulating signal, said lower sideband audio unitmeans comprising filter means connected to the input of said lowersideband audio unit means for passing frequencies below a firstpredetermined level and for passing frequencies above a secondpredetermined level, amplifier means, and means coupling said filtermeans to the output of said lower sideband audio unit means through saidamplifier means, means for supplying a lower sideband input to the inputof said lower sideband audio unit means, frequency shift keying unitmeans having inputs and an output utilizing a frequency shift keyinginput signal for producing at its output a frequency shifted signal inwhich a mark is represented by a signal having a first frequency and aspace is represented by a signal having a second frequency differentfrom said first frequency, said frequency shift keying unit meanscomprising oscillator means connected to an input of said frequencyshift keying unit means and having outputs for producing mark and spacesignals, gate means connected to inputs of said frequency shift keyingunit means and to the outputs of said oscillator means for gating theoutputs of said oscillator means, phase shifting means connected betweenanother input of said frequency shift keying unit means and said gatemeans for phase inverting the frequency shift keying input signal andfor controlling said gate means therewith, and means coupling said gatemeans to the input of each of said upper and lower sideband audio unitmeans through the output of said frequency shift keying unit means,means for supplying a frequency shift keying input signal to the inputsof said frequency shaft keying unit means, continuous wave unit meanshaving inputs and an output utilizing a continuous wave D.C. inputsignal for producing at its output a continuous wave signal, saidcontinuous wave unit means comprising oscillator means connected to aninput of said continuous Wave unit means and having an output and beingenergized by said continuous wave D.C. input signal for producing a tonesignal of predetermined frequency, gate means connected to inputs ofsaid continuous wave unit means and to the output of said oscillatormeans for gating the output of said oscillator means, filter means, andmeans coupling said gate means to the output of said continuous waveunit means through said filter means, and means for supplying acontinuous wave D.C. input signal to the inputs of said continuous waveunit means;

synthesizer means having an output connected to an input of said radiofrequency generating means for supplying stable frequencies to saidradio frequency generating means;

counter means having an input connected to the output of said radiofrequency generating means and another input for indicating thefrequencies of signals produced by said single sideband generatingcircuit arrangement;

calibrator means having an output connected to an input of said radiofrequency generating means and to the other input of said counter meansfor supplying a reference frequency standard signal for said radiofrequency generating means and for said counter means; and

output means connected to the output of said radio frequency generatingmeans for deriving the modulated radio frequency signals from said radiofrequency generating means.

4. Single sideband generating circuit arrangementcomprising, incombination,

modulated double sideband radio frequency carrier producing means forderiving a double independentsideband signal of twice the referencefrequency, means for supplying an upper sideband audio modulation to asecond input of said modulated double sideband radio frequency carrierproducing means, means for supplying a lower sideband audio modulationto a third input of said modulated double sideband radio frequencycarrier producing means, mixed means having two inputs and an output,frequency changing means for producing from said reference frequency asignal of one and one-half times said reference frequency, means forsupplying the one and one-half times the reference frequency signalproduced by said frequency changing means to an input of said mixermeans, means coupling the output of said modulated double sideband radiofrequency carrier producing means to the other input of said mixer meansto produce a double independent sideband signal modulated on a carrierof half the reference frequency at the output of said mixer means toproduce a double independent sideband signal modulated on a carrier ofhalf the reference frequency at the output of said mixer means,bandswitch means having a plurality of bandswitch contacts coupledselectively to the output of said mixer means and coupled selectively tothe output of said modulated double sideband radio frequency carrierproducing means, and a switch arm connected at one end to an outputcontact and adapted to selectively contact at its other end one of theplurality of bandswitch contacts, means connected to the output contactof said bandswitch means for producing a difference frequency betweenstable frequencies supplied thereto and frequencies at the outputcontact of said bandswitch means and for deriving selected sidebandsignals and audio modulated radio frequency carriers from said radiofrequency generating circuit arrangement, and means for supplying stablefrequencies to said last-mentioned means;

audio frequency generating means having an input and an output connectedto an input of said radio fre' quency generating means for producingaudio modulating signals from an upper sideband input and a lowersideband input;

means for supplying upper sideband inputs and lower sideband inputs tothe input of said audio frequency generating means;

synthesizer means having an output connected to an input of said radiofrequency generating means for supplying stable frequencies to saidradio frequency generating means;

counter means having an input connected to the output of said radiofrequency generating means and another input for indicating thefrequencies of signals produced by said single sideband generatingcircuit arrangement;

calibrator means having an output connected to an input of said radiofrequency generating means and to the other input of said counter meansfor supplying a reference frequency standard signal for said radiofrequency generating means and for said counter means; and

output means connected to the output of'said radio frequency generatingmeans for deriving the modulated radio frequency signals from said radiofrequency generating means.

5. Single sideband generating circuit arrangement comprising, incombination,

ratio frequency generating means having a plurality of inputs and anoutput for producing sideband signals and for modulating audiomodulations on a radio frequency carrier, said radio frequencygenerating means comprising,

frequency doubler means having an input and a pair of outputs for"doubling a frequency supplied to it, means for supplying a onemegacycle per second reference frequency standard signal to the input ofsaid frequency doubler means to produce a 2 megacycles per second outputsignal at the output of said frequency doubler means, upper sidebandbalanced modulator means having a pair of inputs and an output, lowersideband balanced modulator means having a pair of inputs and an output,means coupling an output of said frequency doubler means to an input ofsaid upper sideband balanced modulator means for supplying the 2megacycles per second output of said frequency doubler means to saidupper sideband balanced modulator means, means for Supplying an uppersideband audio modulation to the other input of said upper sidebandbalanced modulator means to produce at the output of said upper sidebandbalanced modulator means a modulated double sideband 2 megacycles persecond radio frequency carrier with the carrier partially suppressed,means coupling said output of said frequency doubler means to an inputof said lower sideband balanced modulator means for supplying the 2megacycles per second output of said frequency doubler means to saidlower sideband balanced modulator means, means for supplying a lowersideband audio modulation to the other input of said lower sidebandbalanced modulator means to produce at the output of said lower sidebandbalanced modulator means a modulated double sideband 2 megacycles persecond radio frequency carrier with the carrier partially suppressed,upper sideband crystal filter means for eliminating frequencies below 2megacycles per second, lower sideband crystal filter means foreliminating frequencies above 2 megacycles per second, sideband combinermeans having a pair of inputs and an output for isolating said upper andlower sideband crystal filter means from each other and for mixing theupper and lower sideband signals to produce a 2 megacycles per seconddouble independent-sideband suppressed-carrier signal at its output,means for connecting the output of said upper sideband balancedmodulator means to an input of said sideband combiner means through saidupper sideband crystal filter means, means for connecting the output ofsaid lower sideband balanced modulator means to the other input of saidsideband combiner means through said lower sideband crystal filtermeans, radio frequency amplifier means having an input connected to theoutput of said sideband combiner means, another input and a pair ofoutputs for amplifying the signal at the output of said sidebandcombiner means, relay means connected to the other output of saidfrequency doubler means, gate means coupled between said relay means andthe other input of said radio frequency amplifier means for reinsertingthe carrier suppressed by each of said upper sideband balanced modulatormeans and said lower sideband balanced modulator means in the radiofrequency carrier, mixer means having an input connected to an output ofsaid radio frequency amplifier means, another input and an output,frequency tripler means having an input and an output for tripling afrequency supplied to it, means for supplying said one megacycle persecond reference frequency standard sigml to the input of said frequencytripler means to produce a 3 megacycle per second signal at its output,frequency divider means having an input connected to the output of saidfrequency tripler means and an output for dividing the output signal ofsaid frequency tripler means in half to a 1500 kilocycles er secondsignal, means coupling the output of said frequency divider means to theother input of said mixer means to produce a double independent sidebandsignal modulated on a 500 kilocycles per second carrier at the output ofsaid mixer means, lowpass filter means for eliminating frequencies above500 kilocycles per second, bandswitch means having a plurality ofbandswitch contacts and a switch arm connected at one end to an outputcontact and adapted to selectively contact at its other end one of theplurality of bandswitch contacts, means coupling the output of saidmixer means to selected contacts of the bandswitch contacts of saidbandswitch means through said low-pass filter means to supply a 500kilocycles per second double independent sideband signal to saidlast-mentioned selected contacts of said bandswitch contacts, meanscoupling the other output of said radio frequency amplifier means toselected other contacts of the bandswitch contacts of said bandswitchmeans to supply a 2 megacycles per second double independent sidebandsignal to said last mentioned selected other contacts of said bandswitchcontacts, radio frequency mixer means having an input connected to theoutput contact of said bandswitch means, another input and an output,means for supplying variable frequency oscillator stable frequencies tothe other input of said radio frequency mixer means to produce adifference frequency output signal at the output of said radio frequencymixer means, and output means coupled to the output of said radiofrequency mixer means for deriving selected sideband signals and audiomodulated radio frequency carriers from said radio frequency generatingcircuit arrangement;

audio frequency generating means having an input and an output connectedto an input of said radio frequency generating means for producing audiomodulating signals from an upper sideband input and a lower sidebandinput;

means for supplying upper sideband inputs and lower sideband inputs tothe input of said audio frequency generating means;

synthesizer means having an output connected to an input of said radiofrequency generating means for supplying stable frequencies to saidradio frequency generating means;

counter means having an input connected to the output of said radiofrequency generating means and another input for indicating thefrequencies of signals produced by said single sideband generatingcircuit arrangement;

calibrator means having an output connected to an input of said radiofrequency generating means and to the other input of said counter meansfor supplying a reference frequency standard signal for said radiofrequency generating means and for said counter means; and

output means connected to the output of said radio frequency generatingmeans for deriving the modulated radio frequency signals from said radiofrequency generating means.

6. Single sideband generating circuit arrangement comprising, incombination,

radio frequency generating means having a plurality of inputs and anoutput for :producing sideband signals and for modulating audiomodulations on a radio frequency carrier, said radio frequencygenerating means comprising,

modulated double sideband radio frequency carrier producing means forderiving a double independentsideband signal of twice a referencefrequency having three inputs and an output for producing at its outputa double independent-sideband signal of twice the reference frequency,means for supplying a reference frequency standard signal to an input ofsaid modulated double sideband radio frequency carrier producing meansfor deriving a double independent-sideband signal of twice the referencefrequency, means for supplying an upper sideband audio modulation to asecond input of said modulated double sideband radio frequency carrierproducing means, means for supplying a lower sideband audio modulationto a third input of said modulated double sideband radio frequencycarrier producing means, mixer means having two inputs and an output,frequency changing means for producing from said reference frequency asignal of one and one-half times said reference frequency, means forsupplying the one and one-half times the reference frequency signalproduced by said frequency changing means to an input of said mixermeans, means coupling the output of said modulated double sideband radiofrequency carrier producing means to the other input of said mixer meansto produce a double independent sideband signal modulated on a carrierof half the reference frequency at the output of said mixer means toproduce a double independent sideband signal modulated on a carrier ofhalf the reference frequency at the output of said mixer means,bandswitch means having a plurality of bandswitch contacts coupledselectively to the output of said mixer means and coupled selectively tothe output of said modulated double sideband radio frequency carrierproducing means, and a switch arm connected at one end to an outputcontact and adapted to selectively contact at its other end one of theplurality of bandswitch contacts, means connected to the output contactof said bandswitch means for producing a difi'erence frequency betweenstable frequencies supplied thereto and frequencies at the outputcontact of said bandswitch means and for deriving selected sidebandsignals and audio modulated radio frequency carriers from said radiofrequency generating circuit arrangement, and means for supplying stablefrequencies to said last-mentioned means;

audio frequency generating means having an input and an output connectedto an input of said radio frequency generating means for producing audiomodulating signals from an upper sideband input and a a lower sidebandinput, said audio frequency generating means comprising,

upper sideband audio unit means having an input and an output utilizingan upper sideband input for producing at its output an upper sidebandaudio modulating signal, means for supplying an upper sideband input tothe input of said upper sideband audio unit means, lower sideband audiounit means having an input and an output utilizing a lower sidebandinput for producing at its output a lower sideband audio modulatingsignal, means for supplying a lower sideband input to the input of saidlower sideband audio unit means, frequency shift keying unit meanshaving inputs and an output utilizing a frequency shift keying inputsignal for producing at its output a frequency shifted signal in which amark is represented by a signal having a first frequency and a space isrepresented by a signal having a second frequency different from saidfirst frequency, means for supplying a frequency shift keying inputsignal to the inputs of said frequency shift keying unit means,continuous wave unit means having inputs and an output utilizing acontinuous wave input signal for producing at its output a continuouswave signal, and means for supplying a continuous wave input signal tothe inputs of said continuous wave unit means;

synthesizer means having an output connected to an input of said radiofrequency generating means for supplying stable frequencies to saidradio frequency generating means;

counter means having an input connected to the output of said radiofrequency generating means and another input for indicating thefrequencies of signals produced by said single sideband generatingcircuit arrangement;

calibrator means having an output connected to an input of said radiofrequency generating means and to the other input of said counter meansfor supplying a reference frequency standard signal for said radiofrequency generating means and for said counter means; and

output means connected to the output of said radio frequency generatingmeans for deriving the modulated radio frequency signals from said radiofrequency generating means.

7. Single sideband generating circuit arrangement comprising, incombination,

radio frequency generating means having a plurality of inputs and anoutput for producing sideband signals and for modulating audiomodulations on a radio frequency carrier, said radio frequencygenerating means comprising frequency doubler means having an input anda pair of outputs for doubling a frequency supplied to it, means forsupplying a one megacycle per second reference frequency standard signalto the input of said frequency doubler means to produce a 2 megacyclesper second output signal at the output of said frequency doubler means,upper sideband balanced modulator means having a pair of inputs and anoutput, lower sideband balanced modulator means having a pair of inputsand an output, means coupling an output of said frequency doubler meansto an input of said upper sideband balanced modulator means forsupplying the 2 megacycles per second output of said frequency doublermeans to said upper sideband balanced modulator means, means forsupplying an upper sideband audio modulation to the other input of saidupper sideband balanced modulator means a modulated double sideband 2megacycles per second radio frequency carrier with the carrier partiallysuppressed, means coupling said output of said frequency doubler meansto an input of said lower sideband balanced modulator means forsupplying. the 2 megacycles per second output of said frequency doublermeans to said lower sideband balanced modulator means, means forsupplying a lower sideband audio modulation to the other input of saidlower sideband balanced modulator means to produce at the output of saidlower sideband balanced modulator means a modulated double sideband 2megacycles per second radio frequency carrier with the carrier partiallysuppressed, upper sideband crystal filter means for eliminatingfrequencies below 2 megacycles per second, lower sideband crystal filtermeans for eliminating frequencies above 2 megacycles per second,sideband combiner means having a pair of inputs and an output forisolating said upper and lower sideband crystal filter means from eachother and for mixing the upper and lower sideband signals to produce a 2megacycles per second double independent-sideband suppressed-carriersignal at its output, means for connecting the output of said uppersideband balanced modulator means to an input of said sideband combinermeans through said upper sideband crystal filter means, means forconnecting the output of said lower sideband balanced modulator means tothe other input of said sideband combiner means through said lowersideband crystal filter means, radio frequency amplifier means having aninput connected to the output of said sideband combiner means, anotherinput and a pair of outputs for amplifying the signal at the output ofsaid sideband combiner means, relay means connected to the other outputof said frequency doubler means, gate means coupled between said relaymeans and the other input of said radio frequency amplifier means forreinserting the carrier suppressed by each of said upper sidebandbalanced modulator means and said lower sideband balanced modulatormeans in the radio frequency carrier, mixer means having an inputconnected to an output of said radio frequency amplifier means, anotherinput and an output, frequency tripler means having an input and anoutput for tripling a frequency supplied to it, means for supplying saidone megacycle per second reference frequency standard signal to theinput of said frequency tripler means to produce a 3 megacycles persecond signal at its output, frequency divider means having an inputconnected to the output of said frequency tripler means and an outputfor dividing the output signal of said frequency tripler means in halfto a 1500 kilocycles per second signal, means coupling the output ofsaid frequency divider means to the other input of said mixer means toproduce a double independent sideband signal modulated on a 500kilocycles per second carrier at the output of said mixer means,low-pass filter means for eliminat ing frequencies above 500 kilocyclesper second, bandswitch means having a plurality of bandswitch contactsand a switch arm connected at one end to an output contact and adaptedto selectively contact at its other end one of the plurality ofbandswitch contacts, means coupling the output of said mixer means toselected contacts of the bandswitch contacts of said bandswitch meansthrough said lowpass filter means to supply a 500 kilocycles per seconddouble independent sideband signal to said last-mentioned selectedcontacts of said bandswitch contacts, means coupling the other output ofsaid radio frequency amplifier means to selected other contacts of thebandswitch contacts of said bandswitch means to supply a 2 megacyclesper second double independent sideband signal to said lastmentionedselected other contacts of said bandswitch contacts, radio frequencymixer means having an input connected to the output contact of saidbandswitch means, another input and an output, means for supplyingvariable frequency oscillator stable frequencies to the other input ofsaid radio frequency mixer means to produce a difference frequencyoutput signal at the output of said radio frequency mixer means, andoutput means coupled to the output of said radio frequency mixer meansfor deriving selected sideband signals and audio modulated radiofrequency carriers from said radio frequency generating circuitarrangement;

audio frequency generating means having an input and an output connectedto an input of said radio frequency generating means for producing audiomodulating signals from an upper sideband input and a lower sidebandinput, said audio frequency generating means comprising upper sidebandaudio unit means having an input and an output utilizing an uppersideband input for producing at its output an upper sideband audiomodulating signal, said upper sideband audio unit means comprisingfilter means connected to the input of said upper sideband audio unitmeans for passing frequencies below a first predetermined level and forpassing frequencies above a second predetermined level, amplifier means,and means coupling said filter means to the output of said uppersideband audio unit means through said amplifier means, means forsupplying an upper sideband input to the input of said upper sidebandaudio unit means, lower sideband audio unit means having an input and anoutput utilizing a lower sideband input for producing at its output alower sideband audio modulating signal, said lower sideband audio unitmeans comprising filter means connected to the input of said lowersideband audio unit means for passing frequencies below a firstpredetermined level and for passing frequencies above a secondpredetermined level, amplifier means, and means coupling said filtermeans to the output of said lower sideband audio unit means through saidamplifier means, means for supplying a lower sideband input to the inputof said lower sideband audio unit means, frequency shift keying unitmeans having inputs and an output utilizing a frequency shift keyinginput signal for producing at its output a frequency shifted signal inwhich a mark is represented by a signal having a first frequency and aspace is represented by a signal having a second frequency differentfrom said first frequency, said frequency shift keying unit meanscomprising oscillator means connected to an input of said frequencyshift keying unit means and having outputs for producing mark and spacesignals, gate means connected to inputs of said frequency shift keyingunit means and to the outputs of said oscillator means for gating theoutputs of said oscillator means, phase shifting means connected betweenanother input of said frequency shift keying unit means and said gatemeans for phase inverting the frequency shift keying input signal andfor controlling said gate means therewith, and means coupling said gatemeans to the input of each of 'said upper and lower sideband audio unitmeans through the output of said frequency shift keying unit means,means for supplying a frequency shift keying input signal to the inputsof said frequency shift keying unit means, continuous wave unit meanshaving inputs and an output utilizing a continuous wave D.C. inputsignal for producing at its output a continuous wave signal, saidcontinuous'wave unit means comprising oscillator means connected to aninput of said continuous wave unit means and having an output and beingenergized by said continuous Wave D.C. input signal for producing a tonesignal of predetermined frequency, gate means connected to inputs ofsaid continuous wave unit means and to the output of said oscillatormeans for gating the output of said oscillator means, filter means, andmeans coupling said gate means to the output of said continuous Waveunit means through said filter means, and means for supplying acontinuous wave D.C. input signal to the inputs of said continuous waveunit means;

synthesizer means having an output connected to an input of said radiofrequency generating means for supplying stable frequencies to saidradio frequency generating means;

counter means having an input connected to the output of said radiofrequency generating means and another input for indicating thefrequencies of signals produced by said single sideband generatingcircuit arrangement;

calibrator means having an output connected to an input of said radiofrequency generating means and to the other input of said counter meansfor supplying a reference frequency standard signal for said radiofrequency generating means and for said counter means; and

output means connected to the output of said radio frequency generatingmeans for deriving the modulated radio frequency signals from said radiofrequency generating means.

8. Audio frequency generating circuit arrangement for producing audiomodulating signals comprising, in combination,

upper sideband audio unit means having an input and an output utilizingan upper sideband input for producing at its output an upper sidebandaudio modulating signal;

means for supplying an upper sideband input to the input of said uppersideband audio unit means;

lower sideband audio unit means having an input and an output utilizinga lower sideband input for producing at its output a lower sidebandaudio modulating signal;

means for supplying a lower sideband input to the input of said lowersideband audio unit means;

frequency shift keying unit means having inputs and an output utilizinga frequency shift keying input signal for producing at its output afrequency shifted signal in which a mark is represented by a signalhaving a first frequency and a space is represented by a signal having asecond frequency different from said first frequency;

means for supplying a frequency shift keying input signal to the inputsof said frequency shift keying unit means;

continuous wave unit means having inputs and an output utilizing acontinuous wave input signal for producing at its output a continuouswave signal;

means for supplying a continuous wave input signal to the inputs of saidcontinuous wave unit means;

a plurality of sources of operating voltage; and

switching means interconnecting each of said upper sideband audio unitmeans, said lower sideband audio unit means, said frequency shift keyingunit means and said continuous wave unit means to corresponding ones ofsaid sources of operating voltage for selectively operating said uppersideband audio unit means, said lower sideband audio unit means, saidfrequency shift keying unit means and said continuous wave unit means.

9. Audio frequency generating circuit arrangement for producing audiomodulating signals comprising in combination,

upper sideband audio unit means having an input and an output utilizingan upper sideband input for producing at its output an upper sidebandaudio modulating signal, said upper sideband audio unit means comprisingfilter means connected to the input of said upper sideband audio unitmeans for passing frequencies below a first predetermined level and forpassing frequencies above a second predetermined level, amplifier means,and means coupling said filter means to the output of said uppersideband audio unit means through said amplifier means; means forsupplying an upper sideband input to the input of said upper sidebandaudio unit means;

lower sideband audio unit means having an input and an output utilizinga lower sideband input forproducing at its output a lower sideband audiomodulating signal, said lower sideband audio unit means comprisingfilter means connected to the input of said lower sideband audio unitmeans for passing frequencies below a first predetermined level and forpassing frequencies above a second predetermined level, amplifier means,and means coupling said filter means to the output of said lowersideband audio unit means through said amplifier means;

means for supplying a lower sideband input to the input of said lowersideband audio unit means;

frequency shift keying unit means having inputs and an output utilizinga frequency shift keying input signal for producing at its output afrequency shifted signal in which a mark is represented by a signalhaving a first frequency and a space is represented by a signal having asecond frequency different from said first frequency;

means 'for supplying a frequency shift keying input signal to the inputsof said frequency shift keying unit means;

continuous wave unit means having inputs and an output utilizing acontinuous wave signal for producing at its output a continuous wavesignal;

means for supplying a continuous wave input signal to the inputs of saidcontinuous wave unit means;

a plurality of sources of operating voltage; and

switching means interconnecting each of said upper sideband audio unitmeans, said lower sideband audio unit means, said frequency shift keyingunit means and said continuous wave unit means to corresponding ones ofsaid sources of operating voltage for selectively operating said uppersideband audio unit means, said lower sideband audio unit means, saidfrequency shift keying unit means and said continuous wave unit means.

10. Audio frequency generating circuit arrangement for producing audiomodulating signals comprising, in combination,

upper sideband audio unit means having an input and an output utilizingan upper sideband input for producing at its output an upper sidebandaudio modulating signal; means for supplying an upper sideband input tothe input of said upper sideband audio unit means;

lower sideband audio unit means having an input and an output utlizing alower sideband input for producing at its output a lower sideband audiomodulating signal;

means for supplying a lower sideband input to the input of said lowersideband audio unit means; frequency shift keying unit means havinginputs and an output utilizing a frequency shift keying input signal forproducing at its output a frequency shifted signal in which a mark isrepresented by a signal having a first frequency and a space isrepresented by a signal having a second frequency different from saidfirst frequency, said frequency shift keying unit means comprisingoscillator means connected to an input of said frequency shift keyingunitmeans and having outputs for producing mark and space signals, gatemeans connected to inputs of said frequency shift keying unit means andto the ouputs of said oscillator means for gating the outputs of saidoscillator means, phase shifting means connected between another inputof said frequency shift keying unit means and said gate means for phaseinverting the frequency shift keying input signal and for controllingsaid gate means therewith, and means coupling said gate means to theinput of each of said upper and lower sideband audio unit means throughthe output of said frequency shift keying unit means;

means for supplying a frequency shift keying input signal to the inputsof said frequency shift keying means;

continuous wave unit means having inputs and an output utilizing acontinuous wave input signal for producing at its output a continuouswave signal;

means for supplying a continuous wave input signal to the inputs of saidcontinuous wave unit means;

a plurality of sources of operating voltage; and

switching means interconnecting each of said upper sideband audio unitmeans, said lower sideband audio unit means, said frequency shift keyingunit means and said continuous wave unit means to corresponding ones ofsaid sources of operating voltage for selectively operating said uppersideband audio unit means, said lower sideband audio unit means, saidfrequency shift keying unit means and said continuous wave unit means.

11. Audio frequency generating circuit arrangement for producing audiomodulating signals comprising, in combination,

upper sideband audio unit means having an input and an output utilizingan upper sideband input for producing at its output an upper sidebandaudio modulating signal;

means for supplying an upper sideband input to the input of said uppersideband audio unit means;

lower sideband audio unit means having an input and an output utilizinga lower sideband input for producing at its output a lower sidebandaudio modulating signal;

means for supplying a lower sideband input to the input of said lowersideband audio unit means;

frequency shift keying unit means having inputs and an output utilizinga frequency shift keying input signal for producing at its output afrequency shifted signal in which a mark is represented by a signalhaving a first frequency and a space is represented by a signal having asecond frequency different from said first frequency;

means for supplying a frequency shift keying input signal .to the inputsof said frequency shift keying unit means;

continuous wave unit means having inputs and an output utilizing acontinuous wave D.C. input signal for producing at its output acontinuous wave signal, said continuous wave unit means comprisingoscillator means connected to an input of said continuous wave unitmeans and having an output and being energized by said continuous waveD.C. input signal for producing a tone signal of predeterminedfrequency, gate means connected to inputs of said continuous wave unitmeans and to the output of said oscillator means for gating the outputof said oscillator means, filter means, and means coupling said gatemeans to the output of said continuous wave unit means through saidfilter means;

means for supplying a continuous wave D.C. input signal to the inputs ofsaid continuous wave unit means;

a plurality of sources of operating voltage; and

switching means interconnecting each of said upper sideband audio unitmeans, said lower sideband

1. SINGLE SIDEBAND GENERATING CIRCUIT ARRANGEMENT COMPRISING, IN COMBINATION, RADIO FREQUENCY GENERATING MEANS HAVING A PLURALITY OF INPUTS AND AN OUTPUT FOR PRODUCING SIDEBAND SIGNALS AND FOR MODULATING AUDIO MODULATIONS ON A RADIO FREQUENCY CARRIER; AUDIO FREQUENCY GENERATING MEANS HAVING AN INPUT AND AN OUTPUT CONNECTED TO AN INPUT OF SAID INPUT AND QUENCY GENERATING MEANS FOR PRODUCING AUDIO MODULATING SIGNALS FROM AN UPPER SIDEBAND INPUT AND A LOWER SIDEBAND INPUT; MEANS FOR SUPPLYING UPPER SIDEBAND INPUTS AND LOWER SIDEBAND INPUTS TO THE INPUT OF SAID AUDIO FREQUENCY GENERATING MEANS; SYNTHESIZER MEANS HAVING AN OUTPUT CONNECTED TO AN INPUT OF SAID RADIO FREQUENCY GENERATING MEANS FOR SUPPLYING STABLE FREQUENCIES TO SAID RADIO FREQUENCY GENERATING MEANS; COUNTER MEANS HAVING AN INPUT CONNECTED TO THE OUTPUT OF SAID RADIO FREQUENCY GENERATING MEANS AND ANOTHER INPUT FOR INDICATING FREQUENCIES OF SIGNALS PRODUCED BY SAID SIGNAL SIDEBAND GENERATING CIRCUIT ARRANGEMENT; 